This program is concerned with the basic mechanisms and the treatment of the pulmonary edema associated with the adult respiratory distress syndrome. Basic Mechanisms: Project 1, "The mechanical factors in edema formation", (Hildebrandt) is concerned with how the changes in size of vessels in the alveolar walls with lung inflation is influenced by surface tension. Interstitial pressures are measured directly. Project 2, "Sites of leakage in pulmonary edema," (Butler) looks at the leakage from the alveolar and extra-alveolar vessels at different lung volumes and pressures after damage by toxins and gases; the P.V. relations of the vessels are used to assess interstitial pressures indirectly in edema. TREATMENT: Project 3, "Detection of edema by radiodensitometry," (Figley) uses x-rays to measure lung density. Project 4, "PEEP and ARDS edema," (Butler) has three parts to look at the effects of PEEP on (1) cardiac output in animals, (2) the cardiac output of patients with ARDS, and (3) intracranial pressure and blood flow. Project 5, "Pathophysiology of oleic acid lung injury," (Hlastala) studies the relationship between pathological and physiological changes associated with ARDS in animals. Project 6, "The healing of ARDS edema," (Cheney) uses a chronic dog model of oleic acid ARDS to look at the effects of PEEP and O2 on the physiological healing of ARDS and of steroids and O2 on the histological healing. Redistention edema is studied in a rabbit model. The projects are supported by an Administrative core, a Morphology core and a goat lymphatic fistular core.